A voltage converter can be used to supply power to various kinds of electrical devices, and operates by converting an input voltage received at its input terminal to an output voltage provided at an output terminal of the voltage converter. A voltage converter can take one of many different forms, which may be selected depending on the requirements of the application at hand. For example, the switched mode power supply (SMPS) is a well-known type of voltage converter that is well-suited to use in personal computers and portable electronic devices such as cell phones, for example, owing to its small size and weight, and high efficiency. A SMPS achieves these advantages by switching one or more switching elements such as power MOSFETs at a high frequency (usually tens to hundreds of kHz), with the frequency or duty cycle of the switching being adjusted using a feedback signal to convert an input voltage to a desired output voltage. A voltage converter may take the form of a rectifier (AC/DC converter), a DC/DC converter, a frequency changer (AC/AC) or an inverter (DC/AC), for example.
However, there are applications whose requirements cannot be met by a single voltage converter. For example, the demand for ever faster and more complex signal and data processing has fuelled the need for new generations of signal processing systems having multiple high-performance processors, which are characterised by their need for multiple low supply voltages, high levels of current demand and tight supply voltage regulation requirements. These needs are met by power supply systems such as the Intermediate Bus Architecture (IBA) power supply system, which employ a multi-stage voltage conversion arrangement having multiple voltage converters to provide a number of tightly-regulated voltages from an input power source.
FIG. 1 shows a schematic of a conventional IBA power supply system. The power supply system 100 shown in FIG. 1 is an example of a three-stage power distribution network, wherein from a primary power source is fed to the respective inputs of one or more first-stage voltage converters. More specifically, power from mains voltage sources “Mains A” and “Mains B” is fed to the inputs of each of two first-stage voltage converters, each provided in the form of a Power Input Module (PIM), 110-1 and 110-2. The power output terminals of PIMS 110-1 and 110-2 are both connected via a power bus 120 to the respective inputs of a plurality of second-stage voltage converters. By way of example, two such second-stage voltage converters are shown in FIG. 1, namely DC/DC converters 130-1 and 130-2. The outputs of the DC/DC converters 130-1 and 130-2 are connected via the Intermediate Voltage Bus (IVB) 140 to a plurality of Point-of-Load (POL) regulators, 150-1 to 150-3, each of which delivers a regulated voltage to the load 170. For simplicity, isolation barriers, Bus drivers, Bus isolators and signal filters are not shown in FIG. 1.
Each of the PIMs 110-1 and 110-2, DC/DC converters 130-1 and 130-2, and POL regulators 150-1 to 150-3 shown in FIG. 1 comprises a digitally manageable on-board controller that controls one or more aspects of the respective voltage converter's operation, such as the voltage conversion ratio, start-up procedure and current sharing operation, as well as functions such as over-voltage/over-current protection. The control performed by each controller can be configured by configuration control signals communication to the controller using e.g. the Power Management Bus (PMBus) protocol, via any suitable communication link. PMBus is an open-standard digital power management protocol with a fully defined command language. For example, there are commands for controlling, configuring and monitoring a converter's operating parameters, such as its output voltage, warning and fault thresholds for input or output voltages and currents, temperature etc.
In the present context, the term “configuring” may refer to the process of programming or reprogramming the controller to implement a procedure that may form at least a part of a computer program, module, object or sequence of instructions executable thereby. Configuration may also refer to the process of setting (e.g. by initializing or updating) one or more parameters used by said procedure to control an aspect of the voltage converter's operation. The “configuring” of a voltage converter as used herein should also be understood to refer to the process of re-configuring the voltage converter.
The configuration control signals may, as in the present example, be transmitted to the controller by a Board Power Manager (BPM) 160, which performs functions including system control and monitoring, fault detection etc. In addition to the configuration control signals, the BPM 160 may also transmit signals to enable the PIMs 110-1 and 110-2 to perform voltage conversion so as to apply the voltages generated thereby to the power bus 120.
Each voltage converter includes a power module that generates an operation voltage to power its controller during operation, so that the controller can be configured by configuration control signals and operate to control the voltage converter. The power module generates the operation voltage by converting the voltage provided at the input of the voltage converter to an appropriate level for the controller's logic circuit. In other words, in a conventional programmable voltage converter, power for the controller thereof is derived from the voltage applied to the voltage converter's input terminal during operation. The BPM 160, on the other hand, receives the power required for its operation from a power source external to the BPM 160, typically an auxiliary power converter provided elsewhere in the power supply system 100 (e.g. inside one of the PIMs 110-1 and 110-2), or from the production test system.